<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>jquery</title>
    <script src="/jquerydemo/script/jquery-3.3.1.js"></script>
    <script>
        // jQuery("#h1") == document.getElementById("h1")
        function hello() {
            // $(".title").css("color", "blue")
            //
            // $("input").addClass("btn")
            // // alert($("#username")))

            $("h1:contains('标记')").addClass("btn");
        }
    </script>
    <style>
        .btn{
            color:red;
            border: 3px blue dot-dash;
            size: 20px;
        }
    </style>
</head>
<body>
<h1 id="h1">这是h1标记</h1>

<h1 class="title">这是h1标记233243</h1>
<h1 class="title">这是h1标记3333</h1>
<h1 class="title">这是h1444</h1>
<h1 class="title">这是h1标记444</h1>
<span class="title">这是h1标记444</span>

<hr />
<input type="button" value="提交01" />
<input type="button" value="提交02" />
<input type="text" value="-------value" id="username"/>
<input type="radio" />
<input type="checkbox" />

<input type="button" onclick="hello()" value="点ji我" />
<script>
    $("#h1").css("color", "red")
    $("#h1").css("font-size", "10px")
    $("#h1").css("border", "10px yellow solid")
    // document.getElementById("h1").style.border = ""
</script>
</body>
</html>